Raman or erbium-doped fiber laser using few-mode fiber grating, and long-distance remote sensor for simultaneously measuring temperature and strain by separating temperature and strain components using the same

Abstract

Disclosed are a Raman or erbium-doped fiber laser using a few-mode fiber grating, and a long-distance remote sensor using the same that can simultaneously measure temperature and strain by separating temperature and strain components using Raman amplification or erbium amplification. When a multi-wavelength Raman or erbium-doped laser is configured by means of a short-period fiber grating serving as a few-mode fiber grating at one side of a resonator and a chirped fiber Bragg grating or tunable chirped fiber Bragg grating at the other side of the resonator, multi-wavelength laser signals are generated in different modes. Because wavelength shift and reflectivity vary with a change in temperature and strain, temperature and strain components can be simultaneously measured. Because an optical fiber of several tens of kilometers is used, it can be utilized as a sensing probe of the long-distance remote sensor.

Description

BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The present invention relates to a Raman or erbium-doped fiber laser, and more particularly to a Raman or erbium-doped fiber laser using a few-mode fiber grating that configures a multi-wavelength Raman or erbium-doped fiber laser. [0003] Moreover, the present invention relates to a sensor using a Raman or erbium-doped fiber laser that uses a few-mode fiber grating, and more particularly to a long-distance remote sensor based on a Raman or erbium-doped fiber laser using a few-mode fiber grating that can configure a multi-wavelength Raman or erbium-doped fiber laser using a two-mode fiber grating and that can simultaneously measure temperature and strain by separating temperature and strain components. [0004] 2. Description of the Related Art [0005] Optical fibers are well-known as excellent sensors immune to electromagnetic interference. Currently, the optical fibers are variously applied to measure cracks and tempe...

AI Technical Summary

Benefits of technology

The present invention provides a solution for simultaneously measuring temperature and strain in a long-distance remote sensor using a few-mode fiber grating and a multi-wavelength Raman or erbium-doped fiber laser. The laser uses a few-mode fiber grating with at least two modes and a mirror fiber grating for performing a mirror function and a temperature and strain sensing function. The optical fiber grating is made using a few-mode fiber grating with a few resonant peaks in a wavelength range of the gain medium. The laser can be used for long-distance remote sensing and has applications in various fields such as optical communication and sensing.

Problems solved by technology

However, there is a problem in that signals sensed from a distance of 25 km or more, that is, temperature and strain signals, cannot be appropriately transmitted due to a Rayleigh scattering phenomenon.

Moreover, because of signal noise due to optical-fiber loss and Rayleigh scattering when a conventional broadband light source or ASE of an optical amplifier is used, there is a problem in that it is difficult for a long-distance transmission of a sensor signal to be carried out in a special environment, for example, deep underground or deep underwater.

Because multiple fiber gratings or a special fiber grating must be fabricated for measurement of temperature and strain, there is a problem in that the conventional sensor is complex and inconvenient in use and requires high costs in fabrication thereof.

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